66991895533 has 2 divisors, whose sum is σ = 66991895534. Its totient is φ = 66991895532.

The previous prime is 66991895519. The next prime is 66991895543. The reversal of 66991895533 is 33559819966.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 50750177284 + 16241718249 = 225278^2 + 127443^2 .

It is a cyclic number.

It is not a de Polignac number, because 66991895533 - 2²⁵ = 66958341101 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66991895543) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33495947766 + 33495947767.

It is an arithmetic number, because the mean of its divisors is an integer number (33495947767).

Almost surely, 2^66991895533 is an apocalyptic number.

It is an amenable number.

66991895533 is a deficient number, since it is larger than the sum of its proper divisors (1).

66991895533 is an equidigital number, since it uses as much as digits as its factorization.

66991895533 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 47239200, while the sum is 64.

The spelling of 66991895533 in words is "sixty-six billion, nine hundred ninety-one million, eight hundred ninety-five thousand, five hundred thirty-three".